Vehicle supported aerial equipment, for instance, fire trucks upon which extendable ladders are mounted, require a stable platform to adequately support the apparatus when fully extended. With fire-fighting vehicles of this type it is known to incorporate a torque box into the vehicle frame which is separate from the frame and highly resistant to twisting and deformation. The aerial apparatus is mounted upon the torque box which in turn is supported by the conventional flexible vehicle frame, and outriggers in the form of hydraulically operated ground-engaging jacks are mounted upon the torque box for engaging the ground and provide a stable platform. The use of a separate torque box and vehicle frame substantially increases the cost of manufacture of this type of vehicle.
It is an object of the invention to provide a vehicle frame, particularly a trailer frame, wherein the frame itself is in the form of a torque box highly resistant to twisting, and the frame defines a receptacle for receiving a counterweight material.
A further object of the invention is to provide a vehicle frame suitable for supporting aerial apparatus wherein the frame itself comprises a torque box for supporting the aerial apparatus, hydraulic outrigger ground-engaging supports being formed on the frame, and the frame construction being such as to define a receptacle for receiving a counterweight material.
In the practice of the invention the elongated trailer frame has a generally boxlike transverse cross section. The lateral sides of the frame are formed by channel beams whereby the base of the beams forms the frame sides, and the beam legs are disposed above and below the base, and extend toward the other channel beam.
A bottom plate bridges the lower legs of the channel beams lateral sides, and is welded thereto, and throughout much of the length of the frame the bottom plate is of a width greater than the distance separating the channel beams to add extra weight to the frame. An upper plate bridges the channel beam upper legs and is welded thereto to complete the box section of the frame.
Preferably, the bottom and upper plates are of heavy plate material in order to add to the weight of the frame, and rigidity to resist twisting is provided by the use of a plurality of plate-like K-braces located within the frame extending between the channel beam bases and welded thereto. Preferably, the vertical dimension of the bracing plates is substantially equal to the vertical dimension of the frame, and the lower edge of the bracing plates is welded to the bottom plate.
The receptacle defined by the lateral channel beams and the bottom plate is filled with a counterweight material, such as cement or steel shot, and this material substantially contributes to the weight of the frame to counteract the weight of the extended aerial apparatus. By the use of such low cost counterweight material the weight of the vehicle can be substantially increased at little cost.